Comedian and writer Mark Steel's ban from voting in the Labour leadership election has fired the starting pistol on a raging debate over the vetting process being employed to stamp out so-called "entryism".

Party officials have been rejecting 'affiliated membership' applications from those feared too radically left-leaning, or rival right-wingers, including the former Tory minister Tim Loughton, deemed to be hijacking the competition by attempting to vote in it.

Steel says he was denied a vote in the election to appoint Ed Miliband's successor, claiming he was told "I don't support their values".

Well - an e-mail from Labour says my application has been rejected as I 'don't support their values'. Maybe I was meant to invade Iraq.

Two Labour MPs, Mike Gapes and Tom Blenkinsop, as well as former parliamentarian Tony McNulty, have all suggested Steel's previous associations with other parties should constitute his exclusion from voting in the upcoming leadership battle.

Gapes told The Huffington Post UK: "Support for another party means you can't be a member of Labour; I think the party are right to be very vigorous.

"Just because [Steel's] a famous comedian doesn't mean it should be one rule for him and another for everyone else."

But others have expressed outrage at the writer's ban, some denouncing the decision as "shameful" and "anti-democratic".

Labour's habit of ostracising those who stray is weird and childish. It's a political party, not a faith cult. http://t.co/0lPZ6Fp5bb

Others have pointed to the varying political allegiances of other senior Labour politicians, including party stalwart and ex-secretary of state Peter Mandelson, a former Young Communist League supporter.

On Thursday, Steel finally spoke out on the matter, saying he was "fuming" at Labour executives' decision.

“It’s a standard thing that clearly goes out to everyone. It says there are two reasons [for rejection]. One is that you don’t support the ideals and values of the Labour party. Or you are a member of a rival organisation," he commented.

“I can’t think what that can be, unless it’s Crystal Palace Football Club or my local snooker club in Croydon. Maybe my snooker club is fielding candidates.”